In a semiconductor device manufacturing process, plasma processes such as etching, sputtering, CVD (chemical vapor deposition) and the like are routinely performed on a substrate to be processed, e.g., a semiconductor wafer. Among plasma processing apparatuses for carrying out such plasma processes, capacitively coupled parallel plate plasma processing apparatuses are widely used.
In a plasma processing apparatus, a pair of parallel plate electrodes (an upper electrode and a lower electrode) may be disposed in a chamber, and a processing gas may be introduced into the chamber. By applying power (e.g., microwave power, etc.) to at least one of the electrodes, a high-frequency electric field is formed between the electrodes resulting in a plasma of the processing gas being generated by means of the high-frequency electric field. Subsequently, a plasma process is performed on a wafer by using or manipulating the plasma. Techniques to control the uniformity of the plasma process across the wafer may be desirable.